Endo 6

Question 1

CRH receptor

Answer 1

Gs-linked receptor [cAMP]

Question 2

ADH receptor

Answer 2

Gq-linked receptor [IP3/DAG]

Question 3

ACTH receptor

Answer 3

Gs-linked receptor [cAMP]

Question 4

Glucocorticoids and androgen receptors

Answer 4

nuclear receptors

Question 5

CRH/ADH synthesis and release. Inhibitory influences

Answer 5

alpha 1-adrenergic nerves stimulate pre-pro CRH/ADH gene expression and copulsatile release of both releasing hormones
-physiological levels of cortisol inhibit pre-proTRH/ADH gene expression

Question 6

ACTH synthesis and release

Answer 6

CRH interacts with Gs receptor
-incrases cAMP
-increases POMC synthesis
-increased convertase synthesis 
ADH interacts with Gq linked receptor
-increased IP3/DAG
-Ca2+ mobilization
-increased ACTH release

Question 7

Regulation of steroidogenesis

Answer 7

• cholesterol delivery into the mitochondria is the rate-limiting step in steroidogenesis
• as it enters the inner chamber, it is converted to the steroid, pregnenolone, by the action of the enzyme P450 side chain cleavage
• cholesterol channel allows it to move (insertion of StAR protein into membrane) ACTH sitmulates this insertion into the membrane

Question 8

Adrenocorticosteroidogenesis

Answer 8

• glucocorticoids (controlled by ACTH)
• androgens (controlled by ACTH)
• mineralcorticoids

Question 9

Deactivation and Excretion

Answer 9

Biotransformation
-potent steroids are converted into steroids that have low biological activity and are more water soluble
Conjugation
-formation of steroid sulphates and steroid glucouronides by liver
Excretion
via urine and some via bile

Question 10

Modes of action for adrenocorticosteroisd

Answer 10

genomic effects
-modification of gene expression 
Non-genomic effects
-mRNA stability
-transmembrane currents
-Ca2+ levels
-phosphorylating events

Question 11

Physiological roles of adrenal androgens

Answer 11

• produced in males and females

- excess androgen production can cause hirsuitism/masculination in females

Question 12

Cortisol

Answer 12

• stimulates gluconeogenesis

- cortisol is also released as part of the body’s response to stress

Question 13

Immunosuppressive actions of glucocorticoids

Answer 13

• inhibits chemo-attraction of immune cells for inflammation sites
• decreases cytokine production
• reduces the production of some immune response cells

Question 14

Cortisol excess

Answer 14

cushing’s syndrome

-hyperglycaemia, increased lipolysis and protein catabolism, increased adrenal androgens, increased urination

Question 15

Adrenal cortical insufficiency

Answer 15

addison’s disease
-hypoglycaemia but weight loss due to decreased appetite
-depletion of liver and muscle glycogen
-increased urea, depression, weakness
Waterhouse-Friderichsen Syndrome
-adrenal haemorrhage and insufficiency due to neisseria meningitidis